3) 彼等はいつもの場所にたむろし始めた。
たむろ – gathering, place where people gather
They started gathering in the usual place.

4) 見た目がふつうだからといって、暴走族よりも寛大に扱われるべきだということにはならない。
寛大 -かんだい – tolerance
Just because they look normal, it doesn’t mean they should be tolerated more than a biker gang.

5) 暗唱できるくだりがいくつかあるほどだ。
暗唱 – あんしょう – recite from memory
To the point where he could knew several parts off by heart.

6) 若者の一人が意味不明なことを喚いた。
喚く – わめく – to shout, cry, scream
One of the youths shouted out for an unknown reason.

7) 一年半前に高校を卒業後、塗装会社に就職したのだが、時間を拘束されるわりに得られる金額が少ないことに嫌気がさして、三か月前に退職したのだった。
塗装 – とそう – coating, painting
adjい・な/nounの/verb ＋ わりにB – situation of B does not meet expectations from A (I had a vague feeling of what it meant but I couldn’t put it into words…)
Xに嫌気がさしている – feel disgust for, feel sick of
He graduated high school a year and a half ago and found a job at a paint factory. However, he got sick of the restrictive hours for relatively low pay, so three months ago he quit.

8) 親と顔を合わせたくないからこそ、深夜までこうして外を徘徊しているといえなくもなかった。
徘徊 – はいかい – to wander, loiter
You could even say that it was because he didn’t want to see his parents that he wandered around outside at night.

9) そういう鬱陶しい関係は不要だった。
鬱陶しい – うっとうしい – I knew this could mean gloomy, but it can also mean ‘bothersome/tiresome’ which is more suitable here.
That kind of tiresome relationship was unnecessary.